Cryogenic exhaust gas air conditioner

ABSTRACT

An air conditioner apparatus includes an exhaust pipe having a first end in communication with exhaust gas from an exhaust generating device disposed in a first atmosphere with a first temperature, and a second end discharging the exhaust gas to a second atmosphere with a second temperature; an inlet pipe substantially surrounding the exhaust pipe, the inlet pipe spaced apart from the exhaust pipe for providing a space therebetween and having a first end in communication with the first atmosphere and a second end in communication with the second atmosphere and through which the second atmosphere is introduced into the space; and a guide assembly disposed in the space for guiding the second atmosphere through the space for heat transfer with the exhaust gas moving through the exhaust pipe.

BACKGROUND

The present embodiments relate to apparatus and methods which use exhaust gas to air condition spaces.

Exhaust gas from devices such as, for example, cryogenic freezing systems, is usually vented to waste and in that regard, it is not unusual for a 100% of the exhaust to result in wasted energy. Many production facilities, such as food plants, require a refrigerated atmosphere in which the system is disposed for operation. In such operations, conventional closed loop mechanical refrigeration systems are usually employed.

It would therefore be desirable to be able to use the exhaust gas from, for example, a freezing system in a gas heat exchanger for conditioning air in a plant atmosphere.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present inventive embodiments, reference may be had to the following drawing figures taken in conjunction with the description of the embodiments, of which:

FIG. 1 is a schematic in partial cross-section showing an air conditioner embodiment of the present invention;

FIG. 1A is a schematic view in partial cross-section showing an alternate embodiment of that which is shown in FIG. 1;

FIG. 2 is a side isometric view of a portion of the embodiment of FIG. 1;

FIG. 3 is a top plan view in cross-section taken along line 3-3 of FIG. 1;

FIG. 4 is a side isometric view of a portion of an alternate embodiment of the embodiment in FIG. 2; and

FIG. 5 is a top plan view in cross-section taken along line 5-5 of FIG. 4.

DETAILED DESCRIPTION OF THE INVENTION

The present embodiments provide for exhaust gas from an air conditioner system, such as for example a cryogenic freezer, to be used in a gas-to-gas heat exchanger for conditioning air in a production facility in which the air conditioner is disposed. The present embodiments will reduce the overall power consumption for the production facility, as exhausted or wasted cooling (or heating) potential from the air conditioner is extracted from the exhaust gas and used to condition ambient air of the facility prior to discharging the exhaust from the facility.

Referring to FIG. 1, an air conditioner embodiment is shown generally at 10. The air conditioner 10 is used in connection with, for example, a freezer 12, such as a cryogenic freezer or other exhaust generating device. The cryogenic freezer 12 may be used for chilling any number of different types of products, such as for example food products, and therefore, any number of different types of food products. The freezer 12 may be disposed in a production facility indicated generally at 14 in which a plant atmosphere 16 is present. The production facility 14 includes, as many facilities do, side walls 15, a floor 19 or underlying support surface, and a roof 18. Use of the air conditioner 10 will enable cryogenic exhaust 20 to cool warmer ambient air 22 introduced into the plant atmosphere 16, thereby maintaining said atmosphere 16 in a cool state and obviating the need for additional power to cool the plant atmosphere 16.

The air conditioner 10 includes an exhaust pipe 24 or conduit having a first end 25 connected to the freezer 12 and in communication with a cooling atmosphere 26 of the freezer, an intermediate portion 28 extending from the first end 25 through the plant atmosphere 16 to a second end 30 or external end terminating at and in communication with an exhaust fan 32. The exhaust fan 32 is provided with a discharge pipe 34 for the cryogenic exhaust 20. The exhaust fan 32 is constructed to withdraw the cryogenic exhaust 20 from the freezer atmosphere 26 through the exhaust pipe 28 and thereafter to be discharged to the atmosphere external to the production facility 14. The intermediate portion 28 of the exhaust pipe 24 extends through a hole 36 or port constructed in the roof 18 of the production facility 14.

The hole 36 is constructed and arranged to also accommodate a secondary pipe 40 or conduit which is coaxidal with and extends substantially along an exterior of the intermediate portion 28 of the exhaust pipe 24. A seal 37 or gasket may be disposed at the hole 36 to restrict the warmer air 22 introduced into the pipe 40 from entering directly into the atmosphere 16. The pipe 40 has a first end 42 at the opening 36, a second end 44 terminating at and in communication with a fan 46 disposed within the production facility 14 in the atmosphere 16, and an intermediate portion 43 between the ends 42,44. At least the intermediate portions 28,43 are coaxial for a substantial portion of their respective lengths, wherein the portion 28 is disposed within the portion 43 in spaced apart relationship. The fan 46 includes a discharge pipe 48, such that air 22 external to the production facility 14 is drawn in through the opening 42 of the pipe 40 and down along a space 41 between the pipe 40 and the pipe 28 to be discharged through the pipe 48 into the plant atmosphere 16. The external air 22 is typically warmer than the atmosphere 16 of the production facility 14. The arrangement of the pipes 28,40 and the space 41 therebetween provides for a heat exchanger 50.

Referring to FIG. 1A, another embodiment of the heat exchanger calls for the hole 36 to be sized and shaped to accommodate only the pipe 28 passing through the roof 18. The first end 42 of the pipe 28 is open at an interior of the production facility 14 to thereby draw air from a higher elevation, shown generally at 17, of the atmosphere 16 where the air is at an increased temperature. After which, the heat exchange that occurs between and among the pipes 28,40 would discharge the air at a lower temperature and to a lower elevation of the atmosphere 16 in the production facility 14. Such an embodiment would eliminate operational problems which could arise if the atmospheric conditions external to the production facility 14 include rain, snow or high humidity. Such external adverse conditions could cause ice and snow accumulation in the heat exchanger 50.

Referring also to FIGS. 2 and 3, the pipe 40 is shown in more detail for providing the heat transfer, or gas-to-gas heat transfer effect, provided by the air conditioner embodiment 10. As the cool gas 20 is exhausted through an interior of the pipe 28, the external air 22 is drawn down through the space 41 between the pipes 28,40. A plurality of fins 52 are disposed to extend through the space 41. The fins 52 provide a plurality of pathways 54 along the space 41 to direct the warmer air 22 along the pathways 54 in spaced apart relationship. The fins 52 facilitate the gas-to-gas heat exchange by restricting a particular column of warm outside air 22 introduced through the hole 36 to proceed along one of the paths 54 for continuous exposure to the pipe 28 substantially cooled by the cryogenic exhaust 20. The fins 52 provide additional heat transfer via conduction that occurs between the warm air moving through the pathways 54 being in contact with the fins 52 which have been substantially cooled by conduction occurring as the cryogen exhaust 20 in contact with an interior surface 29 at the pipe 28 becomes cooled. The columns of warm air 22 are cooled upon exposure to the pipe 28. Insulation 56 is disposed at an exterior surface of the pipe 40 to facilitate the heat transfer effect in the space 41 provided by the air conditioner 10.

Accordingly, the warmer outside air 22 drawn into and through the space 41, and restricted to flow as a plurality of columns of warmer air through the pathways 54 is as a result of the disposition of the fins 52, and provides for substantially cooling the air 22 so that it is emitted through the discharge pipe 48 (FIG. 1) into the plant atmosphere 16 at a much cooler temperature. This reduces the cost for the plant operator to cool the plant atmosphere 16. The exhaust gas 20 from the freezer 12 will cool the warm air 22 sufficiently to be introduced into the atmosphere 16.

FIGS. 4 and 5 show an alternative embodiment 60 for the heat exchanger. In this embodiment, the space 41 is provided with a plurality of helical members 62 to provide arcuate or spiral pathways circumscribing the space 41, such that there are a plurality of pathways 64 for the air flow 22 moving through the space 41. Such embodiment requires a greater amount of time for the warmer air 22 introduced into the space 41 to be in contact with the pipe 28 chilled by the cryogen exhaust 20. The warmer air 22 therefore has increased residence time in the pathways 64 of the space 41, such that the exhaust at the discharge 48 (FIG. 1) to the atmosphere 16 may be cooler than the exhaust discharged into the atmosphere 16 by the heat exchanger embodiment of FIGS. 1-3. The insulation 56 can also be used with this embodiment 60.

By way of example, the cryogenic freezer 12 operating at for example −80° F. (−62.2° C.) and the air 22 external to the production facility 14 being at 70° F. (21.2° C.), would result in the warmer air 22 being cooled to a temperature of 45° F. (7.2° C.), and the air 22 at the discharge pipe 34 being at a temperature of 0° F. (−17.8° C.). The speed of the fan 46 can be adjusted to provide a temperature desired for the atmosphere 16. That is, adjusting the speed of the fan 46 will determine the residence time of the warmer air 22 being exposed to the cold of the pipe 28 to bring about the desired temperature of the cooled air being emitted from the discharge pipe 48 into the atmosphere 16. Adjustment of the fan speed can also be used with the air conditioner embodiment having the heat exchangers 50,60.

The air conditioner 10 with the heat exchanger 50,60 operates such that the cold cryogenic exhaust gas 20 is forced through an interior of the pipe 28 of the heat exchanger 50,60, where an internal surface of the pipe 28 is smooth and there is minimal chance for snow or ice build-up to foul the pipe 28 and the process. The fins 52 and the helical members 62 are disposed to bridge the space 41 between the pipes 28,40 to enable more heat to be transferred efficiently as the incoming warmer air 22 is conveyed along the pathways 54,64 in the space 41. The insulation 56 prevents precooling of the warmer outside air 22 by air that has already been cooled in the plant atmosphere 16. The insulation 56 is used and disposed to maximize heat transfer from the colder exhaust gas 20 with the warmer gas 22 (outside air, or air from the elevated location 17 in the atmosphere 16) with minimal effect from the atmosphere 16.

The embodiments shown in FIGS. 2-5 can be used with the air conditioner apparatus 10 of FIGS. 1 and 1A.

For a cryogenic freezing process producing 6,000 lb/hr of product with a heat load of 100 BTU/lb, the present embodiments could yield an additional ten (10) tons of refrigeration capacity for the production facility 14.

Although the above embodiments have been discussed for example with respect to the air conditioner 10 being a cryogenic freezer which provides a cryogenic exhaust 20, the air conditioner 12 could also be a heating apparatus such as an oven where the end result is to maintain a warmer temperature in the plant facility atmosphere 16. That is, the exhaust 20 at an elevated temperature from the oven 12 can be used with the embodiments 50,60 where necessary to maintain or elevate the temperature of the atmosphere 16.

It will be understood that the embodiments described herein are merely exemplary, and that one skilled in the art may make variations and modifications without departing from the spirit and scope of the invention. All such variations and modifications are intended to be included within the scope of the invention as described and claimed herein. Further, all embodiments disclosed are not necessarily in the alternative, as various embodiments of the invention may be combined to provide the desired result. 

1. An air conditioner apparatus, comprising: an exhaust pipe having a first end in communication with exhaust gas from an exhaust generating device disposed in a first atmosphere with a first temperature, and a second end discharging the exhaust gas to a second atmosphere with a second temperature; an inlet pipe substantially surrounding the exhaust pipe, the inlet pipe spaced apart from the exhaust pipe for providing a space therebetween and having a first end in communication with the first atmosphere and a second end in communication with the second atmosphere and through which the second atmosphere is introduced into the space; and a guide assembly disposed in the space for guiding the second atmosphere through the space for heat transfer with the exhaust gas moving through the exhaust pipe.
 2. The apparatus of claim 1, wherein the guide assembly comprises at least one fin arranged in the space to direct a flow of the second atmosphere through the space.
 3. The apparatus of claim 1, wherein the guide assembly comprises a plurality of fins in spaced apart relationship arranged in the space to direct a flow of the second atmosphere through the space.
 4. The apparatus of claim 1, wherein the guide assembly comprises a helical member arranged in the space for providing a plurality of helical pathways circumscribing the space and through which the second atmosphere flows.
 5. The apparatus of claim 1, wherein the exhaust generating device comprises a freezer.
 6. The apparatus of claim 1, wherein the exhaust generating device comprises a heater.
 7. The apparatus of claim 6, wherein the heater comprises an oven.
 8. The apparatus of claim 1, wherein the second atmosphere is external to a location of the first atmosphere.
 9. The apparatus of claim 1, wherein the second end of the inlet pipe is open to an elevated region of the first atmosphere.
 10. The apparatus of claim 1, further comprising insulation disposed at an exterior of the inlet pipe.
 11. The apparatus of claim 1, further comprising a first blower in communication with the second end of the exhaust pipe for moving the exhaust gas through the exhaust pipe, and a second blower in communication with the first end of the inlet pipe for moving the second atmosphere through the inlet pipe.
 12. The apparatus of claim 1, wherein the second temperature is greater than the first temperature. 